Legal Question in Real Estate Law in California

Not if it was deeded to you in fee simple absolute.

It depends on what you mean by "given." Unless she formally transferred title to you, including recording a deed from you to her in the county records, then yes she can. If she only promised it to you in the future and let you live there, you are out of luck. However, just because it was in the grandmother's will doesn't mean she owns it yet. Unless it was probated and put in your mother's name, she may not have any more right to the house than you do at this point. Until you sort out exactly what the legal ownership is on the county records, there is no sure answer to your question.